Daughter of William I, Count of Hainaut and French princess Joan of Valois, Philippa was engaged to Edward, Prince of Wales, in 1326.

[6] Their marriage was celebrated in York Minster on 24 January 1328, some months after Edward's accession to the throne of England and Isabella of France's infamous invasion.

[7] After her husband reclaimed the throne, Philippa influenced King Edward to take interest in the nation's commercial expansion, was part of the successful Battle of Neville's Cross, and often went on expeditions to Scotland and France.

King Edward II decided that an alliance with Flanders would benefit England and sent Bishop Stapledon of Exeter on the Continent as an ambassador.

[12] Four years later, in the summer of 1326, Isabella of France, the Queen of England, arrived at the court of Hainaut to seek aid from Count William in order to depose her husband, Edward II, from the throne.

As the couple were second cousins (as great-grandchildren of Philip III of France), a papal dispensation was required;[13] and sent from Pope John XXII at Avignon in September 1327.

[15] The official marriage was at York Minster on 24 January 1328, eleven months after Edward's accession to the English throne; although the de facto rulers were Queen Mother Isabella and her lover, Roger Mortimer, 1st Earl of March, who jointly acted as his regents.

Shortly afterward, Mortimer was executed for treason and then the Queen Mother was sent to Castle Rising in Norfolk, where she spent a number of years under house arrest but with her privileges and freedom of movement eventually restored.

[17] Philippa proved to be the model of a queen and worked tirelessly for the crown, maintaining balance between royal and familial duties admired in tumultuous times.

As the financial demands of the recent Hundred Years' War were enormous, Philippa wisely advised the King to take interest in the nation's commercial expansion as a different method of covering the expenses.

In 1364 or 1365, Edward III demanded the return of Hainaut and other inheritances which had been given over to the dukes of Bavaria–Straubing in the name of Philippa, but he was unsuccessful as the custom in those regions favoured male heirs.

This event resulted in an English victory and the Scottish King David II being taken prisoner, and held captive for eleven years.

[5] Philippa accompanied her husband on expeditions to Scotland and the rest of Europe in the early campaigns of the Hundred Years War, where she won acclaim for her gentle nature and compassion.

She was also remembered for persuading her husband to spare the lives of the Burghers of Calais, whom he had planned to execute as an example to the townspeople following his successful siege of that port.